Apparatus for controlling the energy-supply for peak demands.



K. A. PAULY.

APPARATUS FOR CUNTROLUNG THE ENERGY SUPPLY FOR PEAK DEMANDS,

APPLICATION mu) IULY 31.19%

1,201,619. Patented (m. 17,1910.

Figv l.

lnQcnLor: Karl APaul f 3%; b fi/zfiaw His Attorney.

K. A. PAULY.

APPARATUS FOR CONTROLLING THE ENERGY SUPPLY F08 PEAK DEMANDS.

APPLICATION HLD1ULY3I.I9|4.

1,201,619. Patented Oct. 17,1916.

2 SHELIS-SHEY 2.

IPA/c ntor- \Nitne ses: W K rl APaUI UNITED STATES PATENT OFFICE.

KARL A. PAULY, OF SQHENECTADY, NET-V YORK. ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

APPARATUS FOR CONTROLLING THE ENERGYSUPPLY FOR PEAK DEMANDS.

Application filed July 31, 1914.

To all whom it may concern: v

Be it known that I, KARL A. PAULY, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Apparatus for Controlling the EnergySupply for Peak Demands, of which the following is a speeification. n

My invention relates to ap aratus for controlling the energy supply Er the peak demands of an electrical installation, and particularly to apparatus for relieving a principal source. of energy supply of the burden of peak loads. a

The object of my invention is to provide a novel and improved apparatus for control-.

ling the energy supply of an electrical installation during the periods ofpeak de mands.: V y

More particularly the object of my invention is to provide a novel and improved apparatus for limiting the averagedemand made by an electrical installation upon a principal source ofen'ergy supply.

More specifically the object of my invention is to maintain the average demand made by an electrical installation upon a principal source of energy supply below a predetermined value.

Peak loads and'particularly sudden or intermittent peaks such as occur from violent fluctuations of load are very 0hjectionable to a central generating station because of thelarge amount of apparatus required to take care of the peak demands, The central station is, therefore, greatlyinterested in equalizing a'consumers demandand particularly in eliminatingpeak demands. To this end, a common form of tariff contract provides an excess charge in the nature ofa penalty whenever the consumers demand upon the central generating station exceeds Usually the conis to obtain the most favorable tariff rate. The consumer's average demand may be determined as the amount of energy consumed in apredetermined time interval, or as the time required to ,consume a predetermined quantity or intervalof energy. In either case the average demand is the average rate of energy consumption during the interval Specification of Letters Patent.

mand the consumer is Patented Oct. 17, 1916.

Serial No. 854,277.

ofaueasurement. Thus a consumer may by this form of contract be given a decidedly attractive tariff rate for the energy used as long as his average demand does not exceed a predetermined amount. If the average demand does exceed the contract maximum de- 611 penalized by an excess charge. y i

A consumer whose energy is supplied under a tarill ontract of the above character is obviously desirous of maintaining his average demand below the contract maxi mum. The novel and improved apparatus of my invention is designed to be used in such instances, and comprises means adapo ed to relieve the principal source of energy supply, as for example the central 1; metating station, of the burden of the )eak-demand when the average demand 0 the installation is in excess of the allowed contract h maximum demand. '75 My invention thus broadly consists, in 1 providing an apparatus in' which an action no h responsive to the average demand of MI-iii electrical installation is obtainedand 'bywhich suitable' means are controlled "fox-48 0 maintaining the average demand below an predetermined value. Inits more complete n52 form my invention consists in providin an apparatus in which an action substantially T proportional to the average demand of an electrical installation upon a. principal '1- source of electric energy is produced dur! 1' ing each of a plurality of successive inter+ vals and which controls a suitable auxiliary: EJ-T". source of energy for supplying energy :theres. at),

from to the installation when the average- 2 demand made by the installation upon them i patentably characteristic "of myI invention; are definitely indicated in the claims ap 17: "a

pended hereto. 3 I The principle of operation of apparatus: emboslying my invention will be understood from the following description taken in con-u.- nection with the accompanying drawings, in y which:

Figures 1 and 2- are rliagra nmaticivieiivs a ,in perspective of two formsi df apparatusr embodying my invention. y p a i As heretofore stated the average demand of aronsiuners installation may be obtained by measuring the amount of energy consumed during a predetermined time interval, or by measuring the time required to consume a predetermined quantity or interval of energy. In either case. the demand is measured during each of a plurality of successive intervals of reference, whether of tinie or energy, and the average demand during any interval of reference is the average rate of energy consumption during that interval.

\Vhile the apparatus which I have illustrated in the accompanying drawings'to explain my invention is particularly. designed to obtain an action responsive to the consumers demand in terms of the amount of energy consumed during a predetermined time interval, it will be evident to those skilled" in. the art that my invention )8 .de'mand below a predetermined value.

Referring to Fig. 1 of the drawings, there is diagrammatically illustrated a principal source of electric energy supply 5, such as or example a central generating station, supplying electric energy over conductors 6 to the translating devices 7 of a consumers.

installation. The consumer has in operative relation to his installation an auxiliary source of energy supply which is adapted to assist or entirely replace'the principal source of electric energy supply whenever the average demand over a predetermined time interval exceeds the contract maximum demand. The auxiliary source of energy supply may-be of, any desired character, such as a turbine or gas-engine-driven dy namo, a hydro-electric dynamo, suitable storage batteries, a flywheel equalizer, or any other convenient or suitable source of energy supply. In Fig. I of the drawings, I have diagrammatically represented by way of example a turbine-driven alternator comprising an elastic fluid turbine unit 8 dircctly connected to the rotating field 9 of the alternator, and a' stator or armature 10 connected to the conductors 6 and adapted to supply energy to the translating devices 7. The field of the alternator is adapted to be excited from the conductors 11 of a direct current source of supply. Steam admission to the turbine is controlled by .electrom'agnetic valves .12 and 13. These valves are designed to be opened and to permit the passage of steam from the steam 'ches't into the turbine upon the energization of their respective cooperating coils (52 and 63, as will be explained in greater detail hereinafter.

An electric meter of the motor type having a rotatable shaft is connected to the 1 system and is adapted to integrate the energy supplied to the consumers installation by the principal source of energy supply In the drawings I have represented an induction watthi iur meter of the well known type. This meter comprises a magnetic core carrying a potential coil 14 and an oppositely positioned magnetic core carrying series coils 15. A metallic disk armature 16 is secured to a pivotally mounted shaft 17 .arm 21 of a bifurcated member is adapted to mesh with thegear 19. The other arm 22 of the bifurcated member carries a gear -23 adapted to mesh witha gear v24. The

gear 24 is time-actuated, that is to say the gear is continuously rotated at substantially uniform speed by the rotating element 25 As shown, the

of a. constant speed motor. constant speed motoris of the shaded'pole type and comprises a magnetic core 27 having an exciting coil 26 connected across the conductors 6 and a short-circuited shading coil 27 covering a portion of one of the pole faces. The rotating element 25 is of the usual dislrarmature type and is operatively positioned in the air gap of the magnetic core of the constant speed motor. Any suitable constant speed driving mechanism may be employed in place of the constant speed motor which I have illustrated, such for example as a clock movement, or any other mechanism which will driv'e the gear 24 at substantially uniform speed so that the movement of the gear will be, in effect,

time-actuated.

The arms 21 and 22 of the bifurcated member are connected to and suitably insulated from the armature 28 of a pair of electromagnets 29. The armature 28 is secured to a pivoted shaft 30 and the construction is such that when the electromagnets 29 are energized the armature israised thereby lifting the gears 20 and 23 out of gizcd or wound up by the rotation of the gear 19 when the gear 20 is in mesh therewith. A pin 32 is secured to the gear 20 and is adapted to engage with the arm 21 to determine the initial position of the gear 20. It will be obvious that when the gear 20 is raised out of mesh with the gear 19 that the spring 31 operates to return the gearto its initial position with the pin 32 engaging the arni '21. A spring 33 is sim larly secured at one end to the gear 23 and at the other end (on fixed part of the an paratus and is arranged to be energized by the rotation of the gear 24 when the gear 23 is in mesh therewith. A pin 34 is also secured to the gear 23 and engaging with the arm 22 determines the initial position of the gear.

The gear 20 carries a contact 35, while the gear 23 carries contacts 36 and 66 each ar ranged for cooperative engagement with the contact 35. The contacts 36 and 66 are insulated from each other and each has a path of movement substantially coincident with the path of movement of the contact 35. When the gears 20 and 23 are in their respective initial positions the contact 36 is slightly in advance of and just out of'operative engagement with the contact 35. A conductor 37 electrically connects the contact 35 to one of the direct current line-conductors 11. A conductor 67 electrically con- Beats the other line-conductor 11 to one terminal of each of the relay coils 62 and 63. The-other terminals of the relay coils 62 and 63 are electrically connected by con ductors 38 .and 68 to the time-actuated contacts 36 and 66 respectively.

A circuit closing device is included in the electric circuit of the magnets 29 and is adapted to be operated at predetermined equal time intervals. This circuit closing 'device' comprises a rotatable contact 39, adapted t0-be driven at constant speed by the rotating element 25 of the constant speed motor, and a cooperating fixed contact 40. It will thus be seen that the movable contact 39 engages itscotiperating contact 40 at equal time intervals, for example once every minute, and thus energizes the electromagnets 29, thereby raising the armature 28 and thus raising the gears 20 and 23 out of mesh with the gears 19 and 24, respectively.

' The operation ofthe apparatus illustrated in Fig; 1 is as follows :The contacts 36 and 66 start from their respective initial positions, slightly iiradvance of the contact 35, and rotate at a uniform 5 sad. The contact 35 simultaneously starts rom its initial position and follows thepontact'36 at a speed proportional to the rate of supply of electric energy to the translating devices 7 by the primary source of supplyfi. Since the" initial position of the contact 36 is slightly in :u'lrance ol the contact 35, the contact must rotate slightly faster than the contact 36 it it is o overtake and engage the latter contact. The speed of rotation of the contact lu is determined by the contract maxi- .79 mum dcnmnd and is such that the extent of movement of the contact from its initial position is at any instant during a predetermined interval a measure of the maximum amount of energy the consumer could have 7'5 used up to that instant of the interval, if his rate of consumption of energy to remain constant for-the entire interval and his contract maximum demand unexcceded. If,

therefore. the rate of energy supply to the 8 0 conslnnefls installation by the source 5 is l". lllllifllln and such that the total energy sup ply for the predoterminod time interval is substantially equal to the contract maximum demand, the contacts 36 and will rotate 8 5" at the same speed and will not engage. If

the retool energy supply to the consumers installation 1S such that the amount of cncrgv supphcd is at any instant smaller than the amount that might have been taken 20' H 1n the same time at a uniform rate forthe I entire interval Without exceeding the con-YT tract maximum demand, the contact 35 will rotate slower than the contact 36, and hen ce'f the contacts will not engage. If, however;

the amount of energy taken by the installa-" f tion during any portion of the predetrmined time interval is greater than could be ',""'-j taken during the same time at a uniform rate for the entire time interval without ex- 'IO'O ceeding the contract maximum, the contact 35 will rotate faster than the contact 36, and thus the two contacts will engage, thereby energizing the relay coil 62 and opening the y assumes a, portion of the load and furnishes energy to the translating devices 7 of such "'i an amount that the primary source of energy" supply 5 is relieved of the burden ofthis peak demand; The auxiliary" source pi;

energy supply may if desired relieve the primary source of energy sup l t such an ex,

tent that the contact 35 will not underany condition travel faster than the contact .36 as long as the two contacts are in engage; ment, and consequently the primary source oi rush an amount of energy for the interval in exces of the maximum cohtracbvalue.

energy supply will not be called upon to fur In the accompanying drawings, however, I have shown two stages in the assumption of the peak load by'the auxiliary source of" energy. If the demand is of such a chara'cter that the contact 35 travels faster than and consequently overtakes the contact 36 the turbo-alternator will carry a definite amount of the total load of the installation, determined by the amount ol steam admitted by the opening of the valve (52. If the demand is a heavy one the contact 35 will cod tinue to travel faster than the contact 36 and will overtake the contact GG thereupon opening the steam admission valve 13. This additional admission of steam causes the turboalternator to carry a larger proportion of the total load, so that the principal source of energy supply will not be called upon to furnish energy in excess of the contract maximum demand. The assumption of the load by the auxiliary source of energy in a plurality of stages results in increasing the load thrown upon the auxiliary source as the energy consumption in the installation iii--- creases. This prevents overloading of the auxiliary source for peaks of short duration, but where a peak exists for a consider able length of time, the longer it lasts the greater will be the load thrown upon the auxiliary source. The series of time actuated contacts is of such width that the meteractuated contact can not under anycondition pass beyond and out of engagementthtrewith, so that once the auxiliary source is thrown into service it will continueto supply energy for the remainder of that,i n -u'\-fal,' unless the average demand made upon the principal source of energysupply alls"below the predetermined value.

At the end of each equal time interval the electromagnets 29 are energized thereby raising the gears 20 and 23 out of mesh with the'gears 19 and 2-1 respectively, whereupon the former gears are returned to their respective initial positions by means-of the springs 31 and 33 respectively. The return of the gears 20 and 23 to their respective initial positions results in deenergizing which ever of the energizing coils of the electromagnetic steam admission valves that load conditions may have caused to be in an energized state at the end of the time interval. It will thus be seen that the auxiliary source of energy supply is always'out of service at the beginning of each predetermined time interval. The time interval may obviously be of any desired length, and is determined by the character of the installation and by local conditions, and ordinarily is some substantially time interval from one minute to one hour. Itwill of course be understood that the engagement of the meteractuated contact 35 with the time-actuated contacts 36 and 66 may be employed in any suitable way to effect the assumption of any desired portion of the total load of the installation by the auxiliary source of supply, and that 'Lhave shown the control of the steamadmission to the turbine upon the enga ement of these contacts merely by way of example for the purpose of explaining the pr nciple of my invention.

It will be evident from the foregoing description that l have provided an apparatus which will limit the amount of energy supplied by the principal source during any time interval to that amount allowed by the consumers contract. lVhe-n at any instant during any time interval the total amount of energy supplied during the preceding fraction of the interval is in excess of what the consumer may take during that same fraction of the interval without exceeding his contract maximum demand, the apparatus operates to throw the load on the auxiliary source of energy supply'. It will be obvious that the value of the average load at which the auxiliary source is brought into operation may be readily adjusted by varying the speed of the time-actuated contact 36, which can be conveniently accomplished by changing the gear ratio of the gears 23 and 24.

In Fig. 2 of the drawings, I have illustrated a slightly modified form of the apparatus. Certain installations possess a fly able length of time. the source of energy supply can be inter- In these installations rupted for a certain substantial time interval without interfering with the operation of the apparatus of the installation. The apparatus illustrated in Fig. 2 is, articularly adapted for use in such insta lations. By the apparatus of Fig. 2, the energy supplied to the installation by the principal source of supply is integrated during each of the predetermined equal time intervals, and whenever the amount of energy supplied and integrated exceeds the contract maximum demand for that period, the installation is cut off from the principal source of supply and the load is carried by the fly wheel capacity of the installation. This will be best understood by reference to Fig. 7

2 of the drawings. Conductors 6 supply energy from a principal source of electric energy supply to the translating device 47. l have illustrated a motor as the translating device having operatively connected thereto a fly wheel 48. The fly wheel is so designed that it will carry the load connected to the motor for a substantial time interval, and

so the motor may be electrically disconnect t is connected to the installation and integrates -the'amount of energy supplied by the principal source to the motor 47. The

rotatable shaft of the meter driyes the gear 20 and contact 35 in precisely the same manner as in the apparatus of Fig. .1, In place of the time actuated contact of the apparatus of Fig. 1, 'I employ in the apparatus of Fig. 2 an adjustable stationary contact 51. The contact 51 is positioned in the path of movementof the contact 35, and

when these contacts engage the relay coil 50 is energized from the conductors 11 of the direct current source of supply. The

15 circuit of the electromagnets 29 is closed at equal time intervals by a constantspced motor, just as in the apparatus of Fig. 1.

The operation of the apparatus of Fig. 2

is as follows :The contact 35 starts at the 1 zobeginning of each time interval from its insitial position and moves ,toward the contact 51 'at a" rate proportional to the 'rate of supply-of energy to the motor 47. The contact Elsie-adjusted to occupy the desired position withrespect to the initial position of the ebntact 35 and in accordance with the pre- "3 determined contract maximum demand. If Ithe' total amount ofenergy supplied to the motor during the predetermined time inter- 30 val is just less 'than the contract maximum.

demand, the contact will travel just to,

'-but not'into operative engagement with, the contact 51. The relay' coil will thus not fbe'energized and the contact 35. will be re- .35 thrned to its initial position by the energir "za'tion of, the electromagnets 29 at the end -of the] time interval. When, however, the

' total amount of energy sup lied to the motor: 47 substantially e'qua s the contract gyinaximum demand for the predetermined time interval, the .contact 35 will engage Witlith'e contact 51 and thereby energize the relaycpil '50 and open the switch switch 49'is' main tained in'its open position 45 for the remainder of that particular time 'interval and the load'corinected to the motor is carried by the inertia of the fly wheel ffl48i 'ffit theend of the time interval the elec'troinagnets 2am energized and the con- -tact 3'5 returnedto. its initial position. The 1 cycle of operation is then repeated, It will thus'beseen that the supplyfof energy to -the installation from the principal source of ,suppl never exceeds a definite predetermine amount during any one of the predbterminede ual'time intervals. enever vtheload on t predetermined contract amount of energy is 'ly fi om the principal source is interrupte and the load of the installation is carried b the fly wheel energy. In this manner peak emands are very satisfactorily taken care of without exceeding the maximum demand allowed by the con- 49. The

einstallation is such that the principal source of energy will he understood that the invention mav be embodied in many other forms than that shown and described. I, accordingly, do not wish to be restricted to the particular forms and constructions disclosed herein by way of example for the purpose of setting forth my invention in accordance with the patent statutes. The terms of the appended claims are, therefore, not restricted to the precise structures disclosed but are intended go to cover all changes and modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:'

1. In an electrical installation, a source of 3.5. electric energy adapted to supply energy to said installation, an electric meter having a rotatable shaft and adapted to integrate the amount of energy supplied to said installation by said source, a rotatably mounted contact having an initial position and adapted to be rotated by said shaft, a second movable contact having an initial position and a. path of movement substantially coin-, eident with that of said first mentioned contact, means'for moving said econd contact at a substahtially uniform speed, means whereby said contacts are intermittently returned to their respective initial positions, and a relay adapted to have its electric circuit controlled by the engagement of said contacts.

2. In an electrical installation, a principal *source, of electric energy adapted to supply energy to said installation, an auxiliary source of energy supply, said principal source of electric energy being normally employed to supply the total energy demand of said installationv while said auxiliary source of energy normally suppliessubstam tially no energy to said installation, means for integratin theeimount ofenergysup plied to said installation by said principal "source during each of a plurality of-equal time intervals,'and means including said last mentioned means whereby the load of said installation is thrown upon said auxil iary source of energy su ply when the am unt of energy supplie by said prineipa source to said installation during any one of said-equal. time'intervalsexceeds a predetermined alue. V J

'3. In ',an', el ect1 1ca1f installation, a source 'Q e i ener y, ada t d. t s pp y e y to s'aid installation; an electriemeter having a rotatable shaft and adapted to intef grate the amount of energysupplied to said installation by said source, a movable memher; having an initial osition and adapted to be moved by s id s aft. means whereby said member is intermittently returned to its initial position, a second movable memher having an initial position and a path of movement substantially coincident with that of said first mentioned member, means for moving said second member at a sub stantially uniform speed, means whereby said member is intermittently returned to its initial position, and means actuated by the engagement of-said members for limiting the amount of energy supplied to said in stallation by said source. I

4. In an electrical installation, principal source of electric energy adapted to supply energy tosaid installation, an auxiliary source of energy adapted to supply energy to said installation, said principal source of electric energy being normally employed to supply the total energy demand of said in stallation while said auxiliary source of energy normally supplies substantially no energy to said installation, means for obtaining an action responsive to the average demand made by said installation upon said principal source of electric energy, and means including said last mentioned means whereb energy is supplied to said installation y said auxiliar source when the average demand made y said installation upon said principal source of electric energy exceeds a predetermined value.

5. In an electrical installation, a source of electric energy adapted to supply energy to said installation, an electric meter having a rotatable shaft and adapted to integrate the amount of energy supplied to said installation by said source, a movable member having an initial position and adapted to be moved by said shaft, :1 second movable member having an initial position and a path of movement substantially coincident with that of said first mentioned member, means for driving said second member at a substantially uni orm speed, means whereby said members are intermittently returned to their respective initial positions, and means actuated by the engagement of said members for preventing the supply of energy in excess of a predetermined amount to said installation by said source during any one of said intervals.

6. In an electrical installation, a principal source of electric energy adapted to supply energy to said installation, an auxiliary source of energy also adapted to supply ener to said installation, and means for caus ng said auxiliary'source'of energy to supply energy to said installation whenever the, average demand made by the installation upon said source over any fraction of a predetermined interval attains a predetermined value.

7. In an electrical installation, a principal source of electric energy adapted to sup ply energy to said installation, an auxiliary stun-re of energy also adapted to supply energy to said ii'istallation, said principal sourre of electric energy being normally employed to supply the total energy demand of said installation u'liile said auxiliary source of energy normally supplies substantially no energy to said installation, means for obtaining an action responsive to theaverage demand made by said installation on said principal source of energy over any fraction of a predetermined interval, and means including said last mentioned means for causing said auxiliary source of energy to-supply energy to said installation whenever the average demand made by the installation upon said principal source of elcctric energy over any fraction of such a predetermined interval attains a predetermined value. l

S. In an electrical installation, a principal source of electric energy adapted to supply energy to said installation, an auxiliary source of energy also adapted to supply energy to said installation, means for obtaining an action responsive to the average demand made by said installation on said principal source of energy over any fraction of a predetermined interval, and means including said last mentioned means for causing said auxiliary source of energy to supply energy to said installation during any part of such a predetermined interval that the average demand made by the installation upon said principal source of energy during the preceding fraction of such interval attains a predetermined value.

9. In an electrical installation, a source of electric energy adapted to supply energy to said installation, a movable member adapted to be moved at a speed substantially proportional to the rate of supply of energy to said installation by said source, a second movable member having a path of move; ment substantially coincident with that of the first mentioned movable member, means for moving said second member at a sub stantially uniform speed, and means whereby the engagement of said members operates to limit the amount of energy supplied to said installation by said source.

10. In an electrical installation, a source of electric energy adapted to supply'energy to said installation, a movable member adapted to be moved at a speed substantially proportional to the rate pf supply of energy to said installation by said source, 'means hereby said me mber is intermittently re turned to an initial positioma second mov-' able member having a path of movement substantially coincident with that of the first mentioned movable member and adapted to be moved at a substantially uniform speed, means whereby said second member is in termittently returned to an initial position. and means actuated by the engagement of not said member, for limiting the amount of energy supplied to said installation by said source during the times said members are in engagement.

11. In an electrical installation, a source of electric energy adapted to supply energy t o said installation, means for obtaining an action responsive to an average demand in excess of a predetermined value made by said installation upon said source during any fraction of any one of a plurality of equal time intervals, and means including said last mentioned means for limiting the amount of energy supplied to said installation by said source at such times as the average demand made by the installation upon said source of energy during the preceding fraction of any one of said equal time intervals attains its predetermined value for such fraction of the time interval.

12. In an electrical installation, a source of electric energy adapted to supply energy to said installatiim, means including an electric meter driven element and a time actuated element for obtaining an action indicative of an average demand in excess of a predetermined value made by said installation upon said source during any fraction of anyone of a plurality of equal time intervals, and means including said last mentioned means for limiting the amount of energy supplied to said installation by said source at such times as the average demand made by the installation upon said source during the preceding fraction of any one of said equal time intervals attains its pre determinr 1 value for such fraction of the time interval.

13. In an electrical installation, 'a principal source of electric ener adapted to supply energy to said instal ation, an auxiliary source of ener also adapted to supply cn' rgy to. said installation, and means for causing said auxilia source of energy to supply energy to said installation. at such times as the averagedemanil made by th installat on upon said principal source ofenergy dur'nig the preceding fraction of any one of a plurality of equgl time intervals .a second movable member having an initial position and a path of movement substantially coincident with that of the first men tioncd movable member, means for moving said second member at a substantially uniform speed. means whereby said members are intermittently returned to their respective initial positions, and means for causing said auxiliary source of energy to supply energy to said installation whenever the ratio of the distances said members have moved from their respective initial positions at tains a predetermined value.

15. In an electrical installation, a principal source of electric energy adapted to supply encrgy to said installation, an auxiliary source of energy also adapted tosupply energy to said-installation, said principal source of electric energy being normally employed to supply the total energy demand of said installation while said auxiliary source of energy normally supplies substantially no energy to said installation, a movable member adapted to be moved at a speed saubstantially proportional to'the rate of slipply of energy to said installation by said pr ncipal source,--a second member positioned in the path of movement of said first mentioned member, and means actuated by the engagement of said members for causing said auxiliary source of energy to supply energy to said installation,

In witness whereof, I have hereunto set my hand this 29th day of July, 1914,

- KARL A. PAULY.

Witnesses:

HELEN Onronn,- MARGARET E. WOOLLEY. 

